ci: Span matrix

Author: jannisborn

.github/workflows/build.yml

@@ -36,19 +36,20 @@ jobs:
         uses: actions/cache@v2
         with:
           path: ~/conda_pkgs_dir  # from: conda-incubator/setup-miniconda@v2
-          key: ${{ runner.os }}-conda-${{ env.CACHE_NUMBER }}-${{
+          key: ${{ runner.os }}-conda-${{ matrix.python-version }}-${{ env.CACHE_NUMBER }}-${{
             hashFiles('conda.yml') }}
 
       - name: Cache pip
         uses: actions/cache@v2
         with:
           path: ${{ matrix.pip_cache_path }}
-          key: ${{ runner.os }}-pip--${{ env.CACHE_NUMBER }}-${{
+          key: ${{ runner.os }}-pip-${{ matrix.python-version }}-${{ env.CACHE_NUMBER }}-${{
             hashFiles('requirements.txt') }}
 
       - name: Conda environment setup
         uses: conda-incubator/setup-miniconda@v2
         with:
+          python-version: ${{ matrix.python-version }}
           activate-environment: pytoda
           environment-file: conda.yml
           auto-activate-base: false
@@ -73,7 +74,7 @@ jobs:
         if: always()
         with:
           status: ${{ job.status }}
-          text: "CI Build ${{ matrix.os }}"
+          text: "CI Build ${{ matrix.os }} Python ${{ matrix.python-version}}"
           author_name: ${{ github.actor }}
         env:
           SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}